Clear Up Misconceptions About Breast Cancer

October 25, 2006|By Hartford Courant

The real risk factors may not be what you would expect

Smoking, genetics and family history are the factors that many women believe are most important in determining risk for breast cancer. Actually, they should be more concerned about reproductive factors -- when they had their first baby and whether they breast-fed; their weight and exercise regimen; and their age. That's according to a study released by Environment & Human Health, a Connecticut nonprofit organization. Here is a summary of discrepancies researchers found between what people think are risk factors and what science shows:

What women think: More than 90 percent of women surveyed believe that having a close relative with breast cancer poses a very important (79 percent) or somewhat important (13 percent) risk factor.

What science says: Approximately 15 percent to 20 percent of women diagnosed with breast cancer will have a significant family history of the disease.

Why it matters: Thinking their risk of breast cancer is significantly lower than it actually is, women without a family history of the disease may not follow screening recommendations.

What women think: Seventy-three percent of women believe that obesity is very important (36 percent) or somewhat important (37 percent).

What science says: The role of weight gain is, the reports says, "complex but significant." Between the ages of 20 and 40, weight gain significantly increases a woman's risk of postmenopausal breast cancer. Studies say that women who are overweight and diagnosed with breast cancer have a greater risk of recurrence and death.

Why it matters: Only a small minority of women mentioned diet (11 percent) or exercise (6 percent) as a way to limit breast cancer risk.

What science says: Recently, studies have shown a limited association between fat intake and breast cancer risk. A recent trial has suggested, however, that women on a very low-fat diet (less than 20 percent) may have less chance of a recurrence. "Many researchers believe that the critical effect of a low-fat diet is its effect on lowering weight," the report says, "thereby reducing tumor growth and progression."

Why it matters: While the belief that low-fat diets help reduce the incidence of breast cancer has been well publicized, the scientific evidence is not certain.

What women think: A large majority of women -- 88 percent -- consider smoking a major contributor to breast cancer risk, and nearly three-quarters considered exposure to secondhand smoke a risk factor.

What science says: "Most studies have failed to support a significant role in breast cancer risk for either active or passive cigarette smoking," the report says, "although a modest risk from early tobacco use cannot be excluded."

Why it matters: While tobacco use is clearly the single, leading public health risk factor in the U.S., women who don't smoke should understand this behavior does not lower their risk of breast cancer. They still need regular screening.

What women think: Forty-two percent of women felt that breast-feeding was very important (14 percent) or somewhat important (28 percent).

What science says: For every 12 months of breast-feeding, a 4 percent decrease in breast cancer risk occurs. Even breast-feeding for shorter lengths of time contributes to risk reduction.

Why it matters: The lowest-ranked of all risk factors were reproductive and hormonal. But the cumulative effect of early onset menses, late-age first pregnancy, limited or no breast feeding, and late onset of menopause can together markedly increase risk. *